1. Field of the Invention
The present invention relates to a moving-state determining device suitable for detection of meandering of a vehicle from an image of a road in front of the vehicle in the vehicle moving direction picked up by a camera mounted on the vehicle, for example.
2. Description of the Related Art
As a technology for detecting meandering of a vehicle from an image of a road in front of the vehicle in the vehicle moving direction picked up by a camera mounted on the vehicle, such a technology is proposed that a white line as a lane marker laid on the road is detected and the position of the vehicle is acquired from information of the white line. This technology is disclosed in Japanese Unexamined Patent Publication No. 2005-267384 (Patent Document 1), Japanese Unexamined Patent Publication No. 2005-258936 (Patent Document 2), and Japanese Unexamined Patent Publication No. 2005-284339 (Patent Document 3), for example. Also, a technology for detection of drowsiness state of a driver from the meandering state of the vehicle and issue of an alarm to prevent drowsy driving is proposed.
However, in the case of driving on a snowy road or non-paved road, it is difficult to detect a white line from the road image. Thus, in this case, since a white-line position as an index to detect the position of the vehicle can not be identified, meandering can not be detected, which is a problem. Particularly, the road image in front of the vehicle in the vehicle moving direction picked up by a camera mounted on a vehicle can be easily varied by being affected by a vehicle tilting such as an inclination in the vehicle moving direction (yaw angle θ) or in the longitudinal direction (pitch angle φ). Thus, when the white line as the above-mentioned index can not be detected, its image processing itself becomes impossible.